This invention relates to a method and apparatus for matching refrigerants. An example of the application of the invention is to the matching of freons, but the invention is applicable to other refrigerant fluids including, fluorocarbons generally, hydrofluorocarbons, and aliphatic and aromatic hydrocarbons. A principal application of the invention relates to techniques for the efficient handling of refrigerant fluids, such as those used in automotive air conditioning systems. References hereafter to freons are to be interpreted as including references also to the other refrigerant fluids mentioned above.
In the case of the maintenance/servicing of automotive air conditioning systems and indeed in other refrigeration systems which undergo such maintenance/servicing there is a distinct technical problem in relation to the specific coolant fluids used which arises from the chemical interaction of these fluids when mixed.
The interaction of different coolant fluids such as those designated as R134a and R12 is not an issue which requires detailed exposition in this application. The technical data relating to the interaction is to be found in the published literature on the subject. Suffice it to say that the interaction occurs and its result is a reduction in the cooling effect of the coolant fluid whereby its effectiveness for its intended function is significantly impaired.
More significantly, the interaction effect is not in the nature of a standard chemical interaction between defined molecular proportions of the two ingredients leading to a defined product which, when produced effectively exhausts the supplies of the reactants. The interaction is more in the nature of an initiation reaction which requires only a modest quantity of one of the reacting freons to commence a continuing reaction with the other. It is not known whether this mechanism involves the production of free radicals but it suffices to say that the consequence of this reaction initiation possibility is the need for scrupulous monitoring by servicing facilities of freon types being handled at any given time so as to avoid admixture. It will be readily appreciated that even a single error in freon identification when pumping out the fluid from a given system undergoing maintenance could lead to the contamination of large numbers of other systems which are subsequently refilled with fluid from a reservoir containing even a small quantity of the mis-identified freon. Such a situation could lead to very substantial costs for repeat servicing of large numbers of motor vehicles.
More specifically, as with all air conditioning systems, an automotive air conditioning unit requires periodic preventative servicing in order to maintain its effectiveness. Furthermore, as faults occur, it is necessary to investigate and effect repairs. In either case the procedure requires that the freon or other gas be removed from the air conditioning unit's reservoir and stored in the service equipment while the integrity of the air conditioning unit is determined. The reclaim process is important because it involves the filtration and dehumidification of the freon.
Likewise, the known different types of freon, such as R12 and R134a, when cross-contaminated produce degradation of the freon concerned. More importantly the air conditioning unit and/or service reclaim unit concerned is itself effectively degraded and incapacitated, thereby, leading to costly servicing work. Moreover, contamination of the service equipment may lead to further cross-contamination of other air conditioning units that are subsequently serviced. This could leave the garage auto AC servicing or service-provider liable for the repairs.